The administration of medicines, rehydration and nutritional formulations by intravenous (IV) infusion is one of the most common medical procedures employed worldwide. Approximately 2.5 billion IV sets are used annually throughout the world. IV infusion is the fastest'way to deliver fluids and medicines throughout the body.
The basic design of the traditional IV flow controller, which has remained unchanged for more than 40 years, is that of a “roller clamp” operated by a thumb wheel. Adjustment of the thumb wheel results in adjustment of the flow rate of the IV solution through compression of an IV drip tubing passing through the device. A typical IV drip set may include a short catheter (needle) for insertion into a vein. The catheter is connected to a length of IV drip tubing, which in turn is connected to a drip chamber inserted into a bag containing the IV drip fluid. The roller clamp is fitted to the IV tubing between the drip chamber and the catheter.
Standard IV drip sets are available in a number of different combinations, including: variable length and diameter of tubing; vents; multi-point injection ports; standard adult IV sets typically having drip chambers with flow rates of 10, 15, 19 or 20 drops per millilitre; standard paediatric IV sets typically having drip chambers with flow rates of 60 drops per ml; and special IV sets with specific, high accuracy drip chambers with flow rates of 60 drops, or more, per ml.
However, the traditional roller clamp exhibits poor accuracy and precision, and is difficult to adjust and operate, making it unsuitable for use by untrained personnel. This inaccuracy is extremely problematic in delivery of therapeutic drug regimes and in the treatment of children, where accurate drug delivery is particularly important. Traditional IV systems also require constant monitoring and adjustment by trained staff, since the flow rate may change over time.
While barely serviceable to the administration of common drug formulations of the 1950s, the roller clamp IV flow controller does not meet the needs of modern clinical treatment regimes. Although various alterations to the standard design have been suggested, none has been entirely successful in solving the problems of this design.
Traditional systems are still widely used in the developing world for all IV clinical applications, including rehydration, drug administration and blood transfusion. However, due to the shortage of trained medical personnel in developing countries, patients are often left to treat themselves or are treated by substantially untrained personnel. Thus, even where developing world patients have access to improved pharmaceuticals and drug treatment regimes, the technology appropriate for delivery of those drugs is generally not available.
The inherent inaccuracy, difficulty of adjustment of conventional IV flow controllers and the reliance on operator calculation of flow rate leads to high incidence of mortality through under-administration of medicines (such as antibiotics, HIV and chemotherapy drugs) and also to increased mortality through inadvertent over-administration of potent chemotherapy and anaesthetic drugs. Thus, patients in developing countries rarely receive the optimum level of clinical care due to over- or under-administration of intravenous medications, often resulting in avoidable fatalities. It is estimated that the over-administration of drugs causes at least 20 million deaths per annum throughout the developing world. This is a “hidden” epidemic because medical staff accept the high mortality rates associated with IV treatments as being normal and when treatment errors occur due to operator error, they are not recorded.
In the developed world, improvements in drug delivery mechanisms have paralleled advances in pharmacology, ensuring safe, accurate and reliable administration of potent drugs. In particular, microprocessor-controlled IV syringe pumps are widely used in the developed world. The higher cost is justified where the cost of medical personnel is high, since these pumps require little monitoring, errors are notified by an audible alarm and drug administration is automatically recorded. However, such drug delivery systems generally cost around US $1500, making them unsuitable for widespread use in poorer countries (although such systems are found in intensive care units in developing countries). Furthermore, the operating costs are relatively high compared to traditional IV systems, and poorer countries generally lack trained support staff for such high-tech equipment. Furthermore, such costly flow controllers are also unsuitable for use in many other cost-sensitive applications. Traditional IV drip systems are also still used in the developed world for certain applications, including hydration therapy, home health care, emergency care etc.
“Dial-a-flow” IV controllers; in which a flow rate can be set using a scale and a dial, are known and provide satisfactory control of flow rates. However, IV fluid passes through the internal parts of such controllers. Therefore, these are disposable, single use devices and are overly expensive for many applications, generally costing about US $5 to $7 per use.
It is an object of the invention to provide a flow controller which provides satisfactory accuracy of flow rate in a cost-effective manner.
It is another object of the invention to provide a flow controller which is reusable, with a long operating life.
It is a further object of the invention to provide a flow controller which is easy to use with minimal training.
It is another object of the invention to provide a flow controller which reduces drift of flow rate over time and prevents accidental adjustment of flow rate.
It is yet another object of the invention to provide a flow controller which will improve the safety and efficacy of IV treatment therapy in the developing world.
Each object is to be read disjunctively with the object of at least providing the public with a useful choice.